Added .copy() method to Point, Rectangle, MatrixD

Signed-off-by: Grant Skinner <info@gskinner.com>
Added tickstart, tickend, drawstart, drawend events to Stage.

Signed-off-by: Grant Skinner <info@gskinner.com>
Improvements to DOMElement redraw to eliminate flicker and reduce layout costs.

Signed-off-by: Grant Skinner <info@gskinner.com>